The Bitcoin exchange says it has suspended transactions and is 'closely monitoring' its situation

Major Bitcoin exchange Mt. Gox said Tuesday it had closed all transactions to protect its website and its users, following concerns about technical issues.

Because of "the potential repercussions on Mt. Gox's operations and the market, a decision was taken to close all transactions for the time being in order to protect the site and our users," the site said in a short statement. "We will be closely monitoring the situation and will react accordingly."

The decision came after a weeks-long suspension of Bitcoin withdraws at Mt. Gox to outside addresses. Mt. Gox has previously said it had suspended Bitcoin withdrawals because of a technical issue it called "transaction malleability," which could allow for fraudulent exploitation of transaction records.

A document posted Tuesday on Scribd.com purports to be an internal "crisis strategy draft" at Mt. Gox. The document says 744,408 Bitcoins are missing due to "malleability-related theft which went unnoticed for several years."

It's unclear if the document is genuine.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is grant_gross@idg.com.